Actuator fob telemetbic systems



g- 1940. 'r. J. SMULSKI ACTUATOR FOR TELEMETHIC SYSTEMS Original Filed May 18, 1931 5 R Y mm m N5 R w o m m/Um JM m 0 M. h 7% Y B Fig.4.

Reiomed Aug. 6, 1940 ACTUATOR FOB SYSTEMS Theodorel. smummmmnuum Anderson Company, Gary, M, a corporation otlndiana riginal No. 2,088,819, dated August 3, 1887, Serlal No. 538,152. May 18, 1981, which is a division of Serial No. 102,341, December 14, 1938. Application for reissue July 31, 1939, Serial No.

5 Claims (CL zoo-a4) This invention relates to indicating instruments of the class in which an indicating receiver portion of the instrument, or indicator, is electrically actuated by a remotely disposed actuating portion of the instrument, or actuator, the two portions of the instrument being interconnected by a suitable electric circuit.

My invention relates more particularly to instruments of this class in which the indicator is adapted to respond to current impulses transmitted thereto over the electric circuit by an impulse-sending actuator.

The instant invention, therefore, relates more particularly to actuators of this class for transmitting electric impulses variably in response to the variations of a variable factor. Such actuators may be caused to respond to any variable factor but herein 1 have chosen to illlustrate and describe the actuator of my invention as responding to movements of a movable element through a range of movement, and more particularly to the movements of a float in a liquid tank whereby the indicator may be caused to indicate the level of liquid in the tank.

It is one of the objects of this invention to provide an improved construction of actuator of the type referred to adapted to transmit to a receiving instrument a succession of electric impulses.

Another object is to provide such an actuator having improved means for adjusting the same to compensate for variations in the manufacture and assembly of the parts thereof.

Another object is to provide such an actuator of the thermo-responsive type and having improved means for compensating for changes of ambient temperature.

Another object is toprovide such an actuator adapted to be injected into a tank containing liquid and provided with improved means for sealing the tank against egress of liquid therefrom at the point of injection.

Another object is to provide, in an actuator of the class referred to adapted to transmitcurrent to a remotely disposed indicating instrument having a movable indicating element, improved means for adjustably varying the transmitted current to adjust the position of the indicator movable element for any given quantity of the variable !actor to which the actuator is responsive.

Another object is to provide, in an actuator of the class referred to, adapted to transmit current to a remotely disposed indicator comprising a movable indicating element and a scale, im-

proved means whereby the actuator may be adjusted to adjust the indicating element to the extremities of its indicating scale, in accordance with preselected extreme values of the variable factor to which the actuator is responsive.

Another object is to provide an actuator of the class referred to provided with adjustment means for adjustably varying the current transmitted thereby to the indicator, whereby an indicating element of the indicator may be adjusted to either of the extremes of an indicating scale thereof and each independently of the other.

Another object is to provide an improved actuator of the type adapted to transmit current impulses over an electric circuit.

Another object is to provide an actuator of the type adapted to transmit current impulses over an electric circuit and to vary the said impulses in response to variations of a variable factor, and having improved means to cause the impulses to vary in response to' variations of the variable factor.

Another object is to provide an actuator of the class referred to comprising a pair of electric contacts and a thermostatic means for engaging and disengaging the contacts. and having improved means for aligning the contacts with each other and for adjusting their relative positions to a predetermined temperature.

Another object is to provide, in an actuator of the class referred to comprising a pair of contacts, movable relative to each other to effect transmission of impulses over an electric circuit, an improved means for adjusting the normal relative position of the contacts.

Another object is to provide, in an electric controller, comprising a pair of relatively movable contacts, an improved mechanism whereby the contacts may be adjusted positionally relative to each other by an adjusting tool.

Another object is to provide, in an electric controller comprising a. pair of contacts movable to engage and disengage each other, an improved supporting means for the contacts whereby they may normally maintain any adjusted position and whereby they may in an improved manner he adjustably moved to vary their normal position.

Other objects will be apparent to those skilled in the art to which my invention appertains.

My invention is fully disclosed in the following description taken in connection with the accompanying drawing, in which:

Fig. 1 illustrates, in front elevational view and toanenlaraedscalaatransmittsrmstrumsntor 'actuatorem yinsmyinvenmtheviewshowimalsoapartofaliquidcontainingtankupon which the actuator ismountedt Fig.2isaviewoftheactuatoroflig. itaken approximately from theplanel oil-"mi;

I'ig.8isaviewsimilartol'ig.lbutwlthone of the frame elements thereof omitted to show interior mechanism thereof;

l'ig.4isatopplanviewoftheactuatorof PlgJdrawntoastilllarger-acaleandwitha cover thereof removed to show inside mechanism thereof;

Pig. 5 is a cross-sectional view taken approximately from the plane I of Fig. 4 and with the said removed cover of Pig. 4 in place;

Fig.6isaviewsimilartol'ig. litakenfromthe plane i of Fig. 4.

Fig. 7 is a fragmentary cross-sectional view taken from the plane I of Fig 4;

Fig.8isaviewofapairofbimetallicelements which I may employ and illustrating a step in the method of making the same;

Fig.9isafragmentaryviewofanadjusting tool which I may employ in connection with the mechanism shown in Fig. 4;

Fig.10isasectionalviewtakenfromthe plane I. of Fig. 3.

Referring to the drawing, Fig. l, I have shown at I an actuator or actuating portion of the instrument of my invention projected into a tank I through a suitable perforation I in the wall thereof and provided with a float 4 adapted to assume different positions of elevation in correspondence with a variable factor such as changes of level of liquid I in the tank. The actuator l comprises improved means for sealing the aperture 3 and comprises means for transmitting over an electric circuit, comprising a battery 0, a ground connection I. for the battery. a circuit wirel,circuitwirelandagroundcircuit ll for the actuator, electric impulses varying in duration in accordance with variations of liquid level in the tank, the electric impulses energizing and actuating an indicating instrument ii to indicate on a scale It thereof by means of a moving needle iithelevel oftheliquid Iinthetankl.

The instrument I I may be any suitable electro-,

responsive instrument. which upon the reception of a succession of current impulses will effect indication upon a scale. The instrument which I prefer to employ is that illustrated and described in U. 8. Patent 2,022,441 issued November 26, 1935, for improvements in Electrical indicating instruments,whichisassignedtothesameassigneeas the present application. and reference may be had thereto for a more complete description of such an instrument. 7 a v The mechanism of the actuator I and which willpresentlybemorefullydescrlbedisenclosedgenerallyorhousedinacasingcomprising a shallow cup-form housing II the bottomof whichisprovided withalargen rforation 'II in which is sealedly inserted. as for example by soldering, a diaphragm l2 constructed from sheet metal and formed of a plurality of concentric corrugations to render the same flexible for a purpose to be described. 'lheopenendof thecupisprovidedwithalaterally extending annular flange It. A cover It formed preferably from'sheet metal is slightly cuppedor dished and has a laterally extending annular flange Ii substantially coextensive with andparalleltotheflangell. 'lhecover-and housing It and II are sealedly joined together toprovideasealedchambertherewithinbya packing washer ll disposed between the flanges II and II and by a plurality of screws or bolts Il clamping the flanges together. The flanges II and II are also provided with a plurality of aligned perforations ll-J8 through which bolts may be projected to secure the actuator as a wholetothewall ofa tanksuch asthe wall 2, Fig. 1, through which the actuator is projected. In Fig. 1 such bolts are shown at ll-ll, and a packing or sealing washer ll, shown in Fig. 6, is disposed on the outer surface of the tank 2 and between the tank and the said joined flanges II and FromFig. 6it willbeseenthataterminalbolt ll is projected through an enlarged clearance perforation in the cover It and is insulated therefrom by washers l2 and ti on opposite sides of the cover. The washer II is seated in a recess III in the inner side of the cover which fits the outer periphery of the washer to prevent lateral shifting of the washer and to hold the bolt in the center of the perforations to insulate it from the cover. When the cover II is put in place, the head of the bolt II is disposed in resilient engagement with a pair of resilient prongs 04- formed on and bent upwardly from a plate II.

The plate as and a sub-base is shown in Fig.

'I are rigidly secured to the housing ll by a pair of bolts 81-" which not only clamps them on the housing but prevents rotational shifting thereof. The plate II and sub-base It are insulated completely by suitable insulating washers Ill-l" and by insulating bushings It enclosing the bolts 81. Y

The sub-base It extends laterally from the bolts 81 and in an intermediate portion has rlveted thereto as at 89 an adjustable auxiliary support 80 the function and purpose of which will subsequently become apparent, and which is formed from a piece of sheet metal and provided with an upstanding lug ll shown in Figs. 4 and 5.

Riveted to the lug ll as at I! is a thermally responsive or bimetal compensating element is in the form of a link, one end of which is looped around the rivet It. At the other end of the element 93 it is linked or looped around another rivet II, which rivet is also projected through a second link-form thermally responsive or bi-metallic element as, which will hereinafter be referred to as a contacting element. The elements ll and ll are disposed in a vertical plane. Preferably the rivet N is riveted tighter than the rivet. 82, so that the two elements, joined at ll may be hingedly or longitudinally adjustably moved around or upon the rivet '2 to adjustably position the outer end of the element 05, and the two elements may be maintained in longitudinal alignment, by adjustment around the rivet II as necessary.

The elements I3 and ll are of link-form, that is, they have longitudinally elongated perforations therein for the following P 9 As is well known, bimetal in planular or sheet form tends to warp convexly on one side and concavely on the other, and if an element of considerable width such as the element It is employed, the tendency to warp concavely transversely would tend to add stillness to the element to prevent its free bending longitudinally, but by providing the longitudinal slot therein the transverse dimension is made relatively small and any tendency to bend in that direction is overcome by the greater tendency to bend in the longitudinal direction.

The longitudinal perforation of the element 99 serves this same purpose and an additional purpose. In devices of this class, in which an element such as the element 99 is to respond to temperature applied thereto by an electric winding, such as the winding 99 to be referred to, it is desirable that the actual mass of metal be limited to a predetermined amount in order that it may properly radiate heat. But in some instances the desired mass of material may not provide a suitable support for a sufficient length of winding wrapped thereon. By constructing the element 99 with the longitudinal perforation therein, the length of winding 99 which it will take may be increased to any desired amount within reasonable limits, and the mass of the element determined by the size of the perforation.

The outer or free end of the element 99 is providedwith an electric contact 91. The element 99 is also provided with a heating winding wrapped thereon in the form of an insulated wire 99, one end of which is grounded on the element 99 as at 99, the other end of which is connected by a wire 99 to the plate 99 as at I99.

An electric contact'support I9I formed from sheet metal has an upstanding lug I92 carrying an electric contact I99 engageable by the electric contact 91 and the contact support I9I has a portion I99 disposed substantially parallel to the diaphragm 12, and at the center of the diaphragm is riveted to an axially downwardly pro- Jecting arm I99 on the outside of the housing 19, the riveted connection being effected by projecting a reduced portion I99 of the arm I99 through a perforation in the diaphragm 12 and through a perforation in the contact support IN, and riveting over the inner end of the reduced portion I99, washers I91 and I99 being disposed on each side of the diaphragm "if desired. The support I9I and arm I95 are thus. rigidly connected to the diaphragm 19 and any movement communicated to the arm I99 from the outside, such for example as moving it toward the right or toward the left as viewed in Fig. 6, will move the electric contact I99 toward or from the electric contact 91.

It will, of course, be understood by those skilled in the art that any other arrangement may be utilized which will cause one electric contact to be moved, in accordance with any movement of the diaphragm, toward or from another electric contact carried by the thermally responsive element.

The rivet 99 is disposed generally directly under the aligned elements 99 and 99 and inter-.-

mediate their opposite ends and the rivet is drawn tight enough to prevent accidental shifting of the support 99 on the sub-base 99, but the support may be adjustably shifted to rock the plate 99 on the rivet 99 as a bearing, and to correspondingly adjust the position of the contact 91 rotatably around the rivet 99, that is, toward and from the contact I99 as will be understood.

To adiustably move the plate 99, the following means is provided. A notch I99 having generally parallel sides is provided in the support 99; and in the sub-base 99, generally aligned with the notch I99 is a perforation I99. A tool such as indicated in Fig. 9 is provided having a body or shank I99 generally of a diameter slightly less than the width of the notch I99 and has projecting from the end thereof an eccentrically I99 when rotated will act as a cam on the walls of the notch I99 to adiustably rotate the support 99.

The adjustment just described is made during the manufacture of the actuator to compensate for variations in the form and assembling of the parts and will dispose the contacts 91 and I99 in what may be called normal relative positions. To align the contacts I99 and 91, the element 99 may be raised and lowered or shifted longitudinally with the hinging or sliding movements described above.

The general operation of my invention electrically considered will now be described. Current may flow from the battery 6, Fig. 1, by wire 1 to ground and thence by wire I9 to tank I, housing 19, Figs. 4, 5 and 6, contact I99, contact 91, heating winding 96, plate'99 to external terminal bolt 9I. Thence the current may flow by wire 9 to the instrument II of Fig. 1 and thence by wire 9 to the battery 9.

Heat developed in the winding 99 will bend the contacting element 95 to break contact at 91I99 whereupon flow of current stops, and the element 95 cools oil, and returns the contact 91 into engagement with the contact I99. Thus the contacts 91I99 are repeatedly opened and closed causing impulses of current to flow over the circuit described. The impulses of current actuate the instrument II to cause the needle I9 thereof to take up a definite corresponding position on the scale I2 of the instrument.

If it is assumed that the voltage source of the circuit containing the actuator is constant the thermal change of the thermally responsive element will be such as to move the electric contact thereon toward and from the other electric contact so that the contacts will be intermittently engaged and the aggregate time of engagement in a given interval will be in correspondence with a given position of the contact, the position of which is determined by the variable factor. Irrespective of whether the voltage source of the circuit is constant or not constant, the thermal change of the thermally responsive element will be such as to cause the contacts to be intermittently engaged so that the aggregate power transmitted by said contacts in a given interval will be in correspondence with a given position of the contact, which is determined by the movement of the flexible portion or diaphragm of the support, which movement is responsive to a variable factor, such as for example, the varying level of a liquid. 7

If the impulses are relatively short in duration, the needle I9 will indicate a point not far from zero and vice versa if the impulses are of longer duration. This results from the inherent characteristics of the receiving instrument which forms no essential part of the instant invention and may be better understood from the reference to the above-mentioned patent.

While for purposes of illustration, I have shown movement of the diaphragm as being eflected by a lever which is responsive to a variable factor, it is to be understood that other means may be employed and that the diaphragm may be made responsive to variable factors other than variations of liquid level.

The duration of the impulses may be varied by moving the contact I99 to different positions and this in the apparatus illustrative of my invention is effected by movement of the support I9I by means of the arm I99 disposed below the diaphragm 19, and means which will now be de- Ill-HI riveted t0 the bottom of the housing I.

scribed is provided to move the arm Ill correspondingly with the variable factor which for purposes of illustration has been chosen to be changes of level of liquid 5 in the tank 2 to cause the needle ll of the instrument to indias at 2 and/or bolted thereto by the bolts The side plates Ill form supports for a number of mechanism elements pivoted therebetween and enclose said parts to protect them from accidental displacement or injury. The arm Ill above described ex ds downwardly between the plates,

-l'1gs. 2 and On its lower end it is provided with a rearwardly extending, rounded projection Ill engaging a vertically or longitudinally disposed face 4 on the short arm Ill of a pivoted lever ili. Thelever lltispivotedasat lll toapairof superimposed preferably identical adjusting elements |ll-'lll, generally of inverted L shape. and formed from flat sheetmetal. As shown in Fig. 10, the horizontal legs of the i. are spread apart to provide two spaced portions ill-Ill between which the lever Ii. is disposed and to which it is rotatably pivoted by the rivet lll extending through the lever and through the portions III. In the vertical leg of the L, a vertically elongated slot III is provided through which the shank of a bolt I" is projected. the nut III of the bolt when drawn up tight clamping the side plates lit-Ill together to cause them to seize and grip the elements lll--l II and thus clamp them immovably. On loosening the nut ill, the plates Ill may, together as a unit, be moved longitudinally adjustablyby means of the slot III to vary the vertical podtion of the lever lit.

The heel of the L abuts rearwardly upon the headlflofarivethavinsashankportionla .Thehead iflmaythusbeoperated'asacamupon rotating it to rock the elements Ill around the bolt I and move the pivot iii adjustably forward and rearwardly. A spring I" preferably formed from resilient wire is looped over a post III between the side plates Ill and has one end it. in engagement with a nose-III on the elements ill, and at its opposite end as at ill engages the forward side of the arm I". The nojcction iltisthusmaintainedalways inpressurecontact with the face Ill and the elements III are held in pressure-contact with time screw head III.

The lever Ill has a relatively long arm Ill below the pivot I" provided with a contact face III preferably disposed substantially in. a plane with the face Ill. A cam head I" formed from relatively thick sheet metal is rotatably or oscillatably moimted on a pivot ill supported by the side plates I" and hasan eccentric camming.

7. face I engaging the face I" of the lever. The

u carryingafloatlofcorkorthelike.

a1,sa1

when the actuator thus constructed is installed as in Fig. l, the float l or fall with changesofliquidlevel andbymeansofthecam lace It! will correspondingly oscillatethe lever l I 0, causing it to take up positions corresponding to the positions of the float, and for each pomtion of the lever I it, the arm I" will move the. contact Ill to a corresponding pomtion, the movement of the arm being communicated tothe con-' tact supp rt Ill bythe yielding movement of the diaphragm I2.

The purpose of the adjustable movements of the elements I ll above described will now be explained. When the apparatus is installed as in Fig. l, and when the float is in its lowermost position, that is with the parts in the position of Fig. 3, the corresponding position of the contact Ill may be such as to cause it to engage the contact ll whereupon current impulses will flow and therefore the needle 13 may be moved from the zero position on the scale. Also, when the float is in its uppermost position, in which condition the contact I will occupy its farthest position toward the contact 91, the impulses of maximum duration which correspondingly flow may or may not cause theneedle 4| to take up a position exactly on the full podtion of the dial. Also, if the actuator should properly control the impulses to correctly indicate zero and full" for one installation, it might not properly indicate for another or similar installation due to diflerences in the size and/or shape of the tank 2-.

It is one of the important features of my invention that the position of the needle II with respect to the scale it may be adjusted by adjustments at the actuator and that the said adjustments may be changed at will by manipulations made externally of the actuator and without the necessity of opening it up to get at the mechanism therein.

Referring to Fig. 3, and with the float in the lowermost position as indicated in that flgure. the lever II will be in its extreme counter-clockwise position, and therefore the arm III will be at its farthest position toward the left. Figs. 3 and 8, and the contact I at its farthest position toward the right. Figs. 6 and 4. Now, by turning the screw head I22, flrst loosening slightly the nut iii if necessary to take oil the clamping pressure of the side plates III on the elements I, the pivot ill may be adjustably moved forwardly and rearwardly until the contact I is at exactly the'correct position to permit the needle II to rest on the zero position. This adjustment will be retained by the frictional mounting of the screw head III by the riveted over end I24.

The cam head It! may now be rocked "to its extreme upper position causing the cam face I I! torockthe leverllitoitsextremeclockwiseposition, correspondingly moving the contact I to the position to produce impulses of maximum duration. If the needle II then comes to rest of! of the "full" position, the adjusting elements ill may be moved longitudinally by means to be described, and by carrying the lever III with them, the relative lengths of the lever arms Ill and III are changed. By moving the lever Ill downwardlyas viewed in Fig. 3, thearm III is made relatively longer and the arm l3l relatively shorter. This will have the eflect of increasing the movement of the arm I" and correspondingly moving the contact 103 farther to the left, Figs. 4 and 6, and increasing the duration of the impulses to cause theneedle II totake up a position nearer the full" position. In this manner the needle may be caused to take up exactly the "full" position desired.

The described longitudinal movement of the elements H9 is guided by the slot I29. In the preferred construction, the spaced portions ll9 9 are disposed in perforations ll|l59 in the plates lili-i l9; and to adjustably move the elements H9, a screw-driver may be inserted in a perforation I90 and between the upper, or lower, edge of the perforation and the horizontal leg of the element Ill to pry the leg downwardly, or upwardly, respectively.

It will be observed that the faces H4 and I9! of the lever iii are parallel to the face I39 on the adjusting elements ll9, which face engages the screw head I22, so that the longitudinal adjusting movement of the lever iii does not change its relative transverse position and does not change the adjustment which previously had been effected by rotation of the screw head I22. Thus the adjustment of the needle at'the full end of the sca e does not change the adjustment at the zero end. After the nut iii has been again clamped tight, the adjustment is fixed thereby.

These two adjustments just described may be effected from the outside of the actuator, the nut l2l being freely accessible and the screw head I22 likewise being freely accessible, a perforation I39 in the side plates being provided for that purpose.

The movements of the contacting element 95 are compensated to neutralize the effect of local or ambient temperature, by means of the compensating element 99. Referring to Fig. 4, any tendency of the element 95 to bend toward the left due to ambient temperature is compensated for by the element 93 tending to bend toward the right around the rigid riveted connection 92.

For this purpose it is desirable that the two elements 99 and 95 be formed from sheet metal of the same thickness and that in riveting them together as at 94, one be turned oppositely to the other with respect to the two different kinds of meal of which they are composed. To insure that the two elements will be of substantially the same thickness in every case so that the compensating action may be predetermined, I employ the following process in the manufacture of elements 93 and 95.

These two elements are stamped from sheet bimetal in a single piece as illustrated in Fig. 8, the portion which is to be the element 93 Joined to the portion which is to be the element 95 by a thin connecting web I49. This integral structure is retained until at the very moment of rive ing the portions together as at 94. At that moment, the two parts are broken apart by severing the web I40, one of the elements is turned upside down and then the two riveted together. By retaining the parts 99 and 95 joined together until the moment of assembly, they are kept in pairs, each pair coming from substantially the same spot in the sheet of bimetal and therefore being of substantially the same thickness in spite of variations in thickness of the sheet of bimetal which may occur from point to point'therein.

As an alternative means to compensate for changes of ambient temperature and the effects thereof upon the bimetallic element carrying the contact 91, the following means may be employed.

The winding 96 on the bimetallic element may be made from wire having a. positive temperature coefilcient. Then upon a change of ambient temperature, for example a rise of ambient temperature, which would tend to supplement the heat of the winding 99, the temperature of the winding will be correspondingly increased and will increase its resistance resulting in a diminution of current flowing therethrough and in a diminution of the heating effects thereof. Thus a rise of ambient temperature is met by a decrease of heating current. By proportioning the size and length of the heating wife 96 to the dimensions of the bimetallic'element, the compensation may be effected in this manner over a wide range of ambient temperature.

In such cases it may be desirable to entirely omit the compensating bimetallic element 93.

My invention is not limited to the exact details of construction shown and described. changes and modifications may be made within the scope and spirit of my invention and without sacrificing its advantages.

I claim:

1. In an electric controller, a main support, an auxiliary support insulated from the main support and adjustable relative thereto, the main support comprising a flexible portion movable responsive to variations of liquid level, a first contact secured to said flexible portion and movable therewith, and a thermostatic element rigidly mounted on the auxiliary support by an end thereof and at its opposite end having a second contact movable toward and from the first contact under thermal change whereby the contacts will be intermittently engaged and the aggregate time of engagement in a given interval at a given voltage will be in correspondence with a given position of the first contact.

2. In an electric controller, a main support adapted to engage the top portion of a liquid container, an auxiliary support insulated from the main support, the main support comprising a flexible portion, a first contact element secured to the flexible portion including an arm depending from and a contact portion disposed above the flexible portion, asecond contact including a thermostatic element rigidly secured to the auxillary support at one end and having a second contact at its opposite end, the second contact being movable toward and from the first contact under thermal change, means engageable with said depending arm for rocking the first contact in correspondence with liquid level whereby the aggregate time during which the contacts are intermittently engaged in a given interval at a given voltage due to thermal change will be determined by the position of the first contact, and the auxiliary support being movable to move the second contact towards and from the first contact.

3. In an electric controller, a main support, an

Many

auxiliary support insulated from the main support and adjustable relative thereto, the main support comprising a flexible portion, a first contact element secured to the flexible portion and including a depending arm and an upstanding contact, means engageable with said arm to rock the contact responsive to variations in liquid level, a thermostatic element rigidly secured by an end to the adjustable support and at its opposite end having a second contact movable toward and from the first contact under thermal change whereby the contacts will be intermittently engaged, the aggregate time of engagement of the contacts in a given interval at a given voltage being determined by the position of the first contact, and the auxiliary support being adjustable to effect bodily movement of the thermostatic element and-contact to relatively adjust the conable therewith, a thermostatic element'rigidl! mounted on the auxiliary support by an end thereoi and atlts opposite end havinga second contact movable toward and from the first con tactunderthermalchangewhereby-thecontactswill be intermittently engaged and the mate timeotengagementat'agiven interval atagiven voltage will be in correspondence with a given position of the first contact. and the thermostatic elementhavlngportionsoiitslengthadaptedto bend in opposite direction longitudinally responsive to thermal change whereby, the position of fltheseoondcontactwillberelativelyunafiected by variation in ambient temperature.

,5. Inanelectricconttollenasupportincluding afiexihleportionmovableinresponsetoa variable factor such as liquid level. an electric contact movable in accordance with the movement of said flexible portion, a second support insulated from said first support and adjustable relative thereto to a normal relative position, a thermally responsive element rigidly secured at one end thereof to said second support and having a second electric contact at the opposite end, the second electric contact being movable under thermal change toward and from the first contact, means engageable with said flexible portion of said first support for moving said first contact in correspondence with liquid level whereby the aggregate power transmitted while the contacts are intermittently engaged in a given interval due to thermal change will be determined by the position of said first contact.

J. SMULSKI. 

